|Ahead of print publication
Impact of ultrasonography-detected pes anserine bursitis on pain and function in patients with primary knee osteoarthritis
Mohamed Mortada, Yomna A Amer, Rabab S Zaghlol
Department of Rheumatology and Rehabilitation, Faculty of Medicine, Zagazig Unversity, Zagazig, Egypt
Rabab S Zaghlol,
Department of Rheumatology and Rehabilitation, Faculty of Medicine, Zagazig Unversity, Zagazig
Source of Support: None, Conflict of Interest: None
Background: Pes anserine bursitis (PAB) is one of the most common causes of knee pain. Hence, this study aimed to compare the pain and function among all primary knee osteoarthritis (KOA) patients with or without ultrasonic-detected PAB and the associated clinical and radiological findings.
Methods: A single-center cross-sectional study was conducted on 245 patients with primary KOA. The more symptomatic knee examined with musculoskeletal ultrasound (MSUS), were then categorized into two groups according to the presence of PAB; PAB was graded from 0 to 2 on a semi-quantitative scale. Radiological grades of Kellgren–Lawrence were recorded. Pain and functional status was assessed by visual analog scale (VAS), Health Assessment Questionnaire-II (HAQ-II), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).
Results: A total of 110 (44.9%) patients were diagnosed with PAB where 91 (82.7%) of them had Grade 1 and only 19 (17.3%) had Grade 2. The presence of PAB was statistically significant related (P < 0.05*) with age, VAS, HAQ-II, WOMAC subscales, synovitis, and radiographic Grades 3 and 4. However, there was no statistically significant difference (P ≥ 0.05) between KOA patients without PAB and KOA patients with PAB, regarding sex, body mass index, Baker cyst, and effusion.
Conclusion: The presence of PAB on MUS is associated with increased pain and disability in KOA. MSUS should be more widely used to establish the association between PAB and symptom severity and disability among KOA patients.
Keywords: Osteoarthritis, pes anserine bursitis, ultrasonography
|How to cite this URL:|
Mortada M, Amer YA, Zaghlol RS. Impact of ultrasonography-detected pes anserine bursitis on pain and function in patients with primary knee osteoarthritis. Indian J Rheumatol [Epub ahead of print] [cited 2020 Feb 18]. Available from: http://www.indianjrheumatol.com/preprintarticle.asp?id=277935
| Introduction|| |
Pes anserine bursitis (PAB), inflammation of the bursa beneath the conjoined insertion of the pes anserine muscle group tendons along the proximal medial portion of the tibia, can affect an individual's normal regular daily function as much as intra-articular pain.,
Determining variations in the sonoanatomic position of PAB before treatment is important since, although PAB lies within the usual position, it also appears to exist between the pes anserine tendons and the medial collateral ligament and among the tendons of the sartorius, gracilis, and semitendinosus.,
PAB commonly presents as medial or posteromedial knee joint pain and tenderness., Addressing concomitant PAB among patients with symptomatic knee osteoarthritis (KOA) is important in clinical practice to ensure good management., Since approximately 20%–45% of symptomatic KOA patients develop PAB,,,, it should be considered a factor that increases pain among KOA patients, and its early treatment can potentially decrease the need for unnecessary surgical procedures.,
It is generally difficult to identify PAB using clinical examination findings alone because of the unique anatomic structures in the medial portion of the knee. Musculoskeletal ultrasonography (MSUS) can be a routine diagnostic tool for guiding PAB screening and treatment among KOA patients., Clinical studies have also shown that PAB can be treated successfully with conservative treatments such as rest, physiotherapy, and/or steroid injections.,
Therefore, the present study aimed to compare pain, function, clinical and radiological findings among primary KOA patients with or without ultrasonography-detected PAB.
| Methods|| |
Study design and setting
A single-center cross-sectional study was done in the outpatient clinics of the Rheumatology and Rehabilitation Department, Zagazig University Hospitals, from January 2013 to January 2019.
The current study included 245 consecutive patients (24 men and 221 women) aged 35 years or older who complained of chronic unilateral or bilateral knee pain with or without clinical pes anserinus tendinitis bursitis syndrome (PATBS). This diagnosis was based mainly on clinical presentation, and all patients were evaluated using the American College of Rheumatology clinical classification criteria for KOA.
The exclusion criteria were other causes of arthritis such as rheumatoid or infection, history of malignancy or trauma, history of current stroke and neurological diseases, history of any knee surgeries or known bony knee deformities, hip disorders, having received a local knee injection in the last month, and secondary KOA.
A full history and full clinical locomotor and neurological examinations were performed of all included patients. The height and weight of each patient were recorded for body mass index (BMI) calculation.
The following parameters were measured for the more symptomatic knee to assess the knee pain severity and functional capability:
- Visual analog scale (VAS): Is a subjective measure for evaluation of pain intensity on a scale of 0 (no pain) to 10 (extreme pain)
- Health assessment questionnaire-II (HAQ-II): Is a reliable and valid 10-item functional questionnaire over the past week and correlated more with clinical variables than the other HAQ scales
- “Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC): Is calculated based on the Likert version. The index is divided into three subscales: pain (five items), stiffness (two items), and physical function (17 items). The minimum score was 0, and the maximum score was 96 (20 points for pain, 8 points for stiffness, and 68 points for physical function).”
Routine weight-bearing anteroposterior and lateral knee radiographs were taken and analyzed by a rheumatologist who was blinded to the clinical and MSUS findings. Severity was assessed, and the patients were graded from 0 to 4 according to Kellgren–Lawrence grading (KLG). A KLG score <2 was designated as mild osteoarthritis (OA), 2 as moderate OA, and >2 as severe OA.
MSUS evaluations were conducted on the more affected knee by a rheumatologist, who was experienced in this procedure and blinded to the clinical and radiographic evaluations. All patients were examined using B-mode (gray scale) real-time MSUS (F37; Hitachi-Aloka, Japan) interfaced with a 10–18-MHz linear array transducer. According to the European League Against Rheumatism and the outcome measures in rheumatology knee ultrasound recommendations, the joint was tested in the anterior longitudinal and transverse planes.
The unilateral knee was evaluated sonographically for PAB detection and grading. The participants were placed in the supine position with the knee bent at a 5°–10° angle, and ultrasound imaging was performed on the medial aspect of the knee. To differentiate between PAB inflammation grades on ultrasonography, the authors developed a semi-quantitative scale (0–2) as follows: Grade 0, normal hyperechoic picture of pes anserine tendons without tendonitis or bursitis; [Figure 1] Grade 1, mild hypoechogenicity and/or mild swelling or mild loss of fibrillar pattern of the pes anserine tendon and/or mild anechoic effusion related to the tendons; [Figure 2] and Grade 2, marked hypoechogenicity and/or large swelling or marked loss of the pes anserine tendon and/or marked anechoic effusion related to the tendons [Figure 3]. Joint effusion was also detected as an anechoic area, and synovitis was defined as hypoechoic, nondisplaceable, and poorly compressible synovial hypertrophy with a thickness >2 mm in a prone position. Baker's cyst was identified as an anechoic area between the medial gastrocnemius and semimembranosus tendons.
|Figure 1: Longitudinal ultrasonographic scans: show normal hyperechoic pes anserine bursa|
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|Figure 2: Longitudinal ultrasonographic scans: show mild hpoeechogenicity denoting grade one bursitis|
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|Figure 3: Longitudinal ultrasonographic scans: show grade two bursitis with marked hypoechogenicity|
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The recruited 245 patients were further categorized into two groups based on the presence of PAB detected by MSUS as the following: Group I: Included KOA patients without PAB (n = 135) and Group II: Included KOA patients with PAB (n = 110).
The study was approved by the Institutional Review Board at the Faculty of Medicine, Zagazig University Hospitals and by the Rheumatology and Rehabilitation Department at the same University. It has been carried out in accordance with the code of ethics of the world medical association (Declaration of Helsinki 1964) for studies involving humans. A written informed consent was obtained from each participant.
The collected data were coded, entered, and analyzed by computer using a database software program, Statistical Package for Social Sciences (SPSS) (Version 20.0. IBM Corp., Armonk, NY, USA). Quantitative variables were expressed as the mean ± standard deviation (and median for not normally distributed data), whereas the qualitative variables were expressed as a number and percentage. For quantitative variables, independent samples t-test (t) was used as appropriate for normally distributed data, whereas nonparametric data were evaluated with Mann–Whitney U-test. Chi-square test was used to detect the relation between different qualitative variables. Multivariate analysis was performed to detect the determinants of anserine bursitis among OA patients. The results were considered statistically significant and highly statistically significant when the significant probability (P value) was < 0.05* and < 0.001**, respectively.
| Results|| |
A total of 245 primary KOA patients (24 males and 221 females; mean age: 54.8 ± 8.8 years) were classified into Group I (without PAB, n = 135 [55.1%]) and Group II (with PAB, n = 110 [44.9%]). Of note, among the 110 ultrasonography-detected PAB patients, 30 (30%) were diagnosed with PATBS. Patients with PAB had a significantly higher mean age and VAS, HAQ-II, WOMAC pain, WOMAC stiffness, WOMAC physical function, and WOMAC total scores than patients without PAB. Moreover, there was a statistically significant difference in synovitis and radiographic severity between KOA patients without anserine and those with anserine (P < 0.05*). However, no statistically significant intergroup difference (P ≥ 0.05) was found in sex, BMI, Baker's cyst, or effusion [Table 1].
|Table 1: Demographic, clinical, and musculoskeletal ultrasound findings among 245 osteoarthritis knees|
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[Table 2] shows that there was no statistically significant relationship (P ≥ 0.05) between PAB grade and the radiological grade among KOA patients with PAB.
|Table 2: Relation between grading of pes anserine bursitis and the radiological finding among osteoarthritis patients with pes anserine bursitis|
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The results of the multivariate analysis demonstrated that patients aged >55 years were 1.6 times more likely to have PAB (odds ratio [OR]: 1.6; 95% confidence interval [CI]: 0.93–1.59; P = 0.9). In addition, patients with a WOMAC pain scale >3, WOMAC stiffness score >1, WOMAC physical function score >8, and WOMAC total score >12 were 2.5, 3.2, 3.3, and 1.9 times more likely to have PAB (OR: 2.5; 95% CI: 1.49–4.20; P < 0.001**), (OR: 3.2; 95% CI: 1.91–5.5; P < 0.001**), (OR: 3.3; 95% CI: 1.93–5.7; P < 0.001**), and (OR: 1.9; 95% CI: 1.2–3.3; P = 0.01*), respectively. In addition, patients with a VAS score >6 and HAQ-II score > 8 were 2.3 times more likely to have PAB (OR: 2.3; 95% CI: 1.34–3.91; P = 0.003*). Regarding synovitis and radiographic findings, patients with synovitis Grades 3 and 4 were 2.6 and 2.1 times more likely to have PAB (OR: 2.6; 95% CI: 1.22–5.41; P = 0.01* and OR: 2.1; 95% CI: 1.09–3.92; P = 0.02*) [Table 3].
|Table 3: Multivariate regression analysis determinants of pes anserine bursitis among osteoarthritis patient|
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| Discussion|| |
KOA, the most frequently reported joint disease in the knee, is associated with intra-articular and periarticular structures such as ligaments, subchondral bones, capsules, tendons, muscles, and bursa. PATB is among the most important causes of periarticular pain. PAB is a self-limiting disorder, in which the time to improvement ranges from several months to 3 years. Consequently, early detection and appropriate treatment are essential. Therefore, this study aimed to compare the pain and function among all primary KOA patients with or without ultrasonography-detected PAB and the associated clinical and radiological findings.
The present study showed that PAB was detected in 44.9% (110/245) of the painful knees of the included KOA patients. In agreement with the findings of the previous reports, in which the prevalence of PAB among KOA patients was as high as 40%–75%.,, However, the result at hand was much higher than the incidence of bursitis on ultrasonography in 20% (34/170) of patients as mentioned in other reports. We assume that the recorded low prevalence rate in that study may have resulted from different sample sizes and the inclusion of patients with focal symptoms at the attachment site of the pes anserinus.
In addition, the mean age of PAB patients was significantly higher than that of patients without PAB. This supports the findings of many other previous studies., In addition, we found no statistically significant intergroup difference with regard to sex. Similarly, another study determined no relationship between sex and the prevalence of bursitis. However, other published studies reported a higher prevalence of PAB among females.,
We also observed that patients with PAB had significantly higher mean VAS, HAQ-II, WOMAC pain, WOMAC stiffness, WOMAC physical function, and WOMAC total scores than patients without PAB, indicating that PAB is related to clinical parameters, decreases function, and increases joint pain and stiffness. This was in line with the findings of a previously published study.
The above mentioned result matched the findings of another cross-sectional population analysis of 745 adults aged 50 years and older with knee pain, which showed that the incidence of PAB among OA cases also increased with age and concluded that nonarticular conditions around the knee joint should be included in epidemiological studies since they influence pain severity and functional disability.
On assessing the radiographic severity among the included groups, we found a statistically significant difference (P < 0.05*) between KOA patients without PAB and those with PAB. Consistent with the study conducted by Uysal et al., which reported a significant relationship between KOA grade and the incidence of PAB since there was no bursitis in Grade 1 patients, 22.4% (13/58) prevalence of bursitis in Grade 2 patients, 22.2% (14/63) prevalence of bursitis in Grade 3 patients, and 30.4% (7/23) prevalence of bursitis in Grade 4 patients. This result is in contrast with the study by Yoon et al. who prospectively analyzed the ultrasound results of 26 female patients with KOA and found that the incidence of PAB was not related to age or radiological OA grade and that there was no relationship with BMI.
The assessment of other US findings demonstrated a statistically significant intergroup difference (P < 0.05*) regarding synovitis, while no statistically significant difference (P ≥ 0.05) was found with regard to the frequency of Baker's cyst and effusion. Furthermore, there was no statistically significant relationship (P ≥ 0.05) between PAB grading and radiological severity among KOA patients with PAB. To the best of our knowledge, no previous studies have investigated the relationship between PAB grading and radiological severity. However, other reports indicated that radiographically severe KOA may have considerable variation in clinical symptom severity. Therefore, there is a discrete correlation between clinical and radiographic results among KOA patients.
Hence, after multivariate analysis, the key findings in the present study were the significant relationship of the presence of ultrasonography-detected PAB with VAS, HAQ-II, and WOMAC subscale (pain, stiffness, physical function, and total) scores and radiographic severity (P < 0.05).
Another study examined 157 women (314 knees) with KOA and 30-matched healthy female controls (60 knees) without knee pain to determine the ultrasonography findings of the pes anserinus tendon and bursa. The authors concluded that KOA patients with clinical PATBS had considerably more PAB and higher VAS values than KOA patients without PATBS, indicating that the presence of PAB is associated with knee pain severity.
Moreover, KOA and PAB can coexist, and clinical PATBS may be seen in one or both knees in KOA patients; in such cases, PAB may be the cause of knee pain. PAB is an easily treatable cause of knee pain. Its early detection and management are crucial and can significantly improve pain and function, which can positively impact the patient's quality of life.
The key limitation of this study was the lack of a younger population without joint pain or KOA for the comparison of the prevalence and risk factors of PAB in a cohort of healthy individuals. Another limitation is its cross-sectional nature, as only a longitudinal study would be able to determine whether specific PAB treatment would improve functional outcomes.
| Conclusion|| |
The presence of PAB on MUS is associated with increased pain and disability in KOA. MSUS should be more widely used to establish the association between PAB and symptom severity and disability among KOA patients.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]